53 lines
1.6 KiB
Rust
53 lines
1.6 KiB
Rust
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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// In theory, it doesn't matter what order destructors are run in for rust
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// because we have explicit ownership of values meaning that there's no need to
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// run one before another. With unsafe code, however, there may be a safe
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// interface which relies on fields having their destructors run in a particular
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// order. At the time of this writing, std::rt::sched::Scheduler is an example
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// of a structure which contains unsafe handles to FFI-like types, and the
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// destruction order of the fields matters in the sense that some handles need
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// to get destroyed before others.
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//
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// In C++, destruction order happens bottom-to-top in order of field
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// declarations, but we currently run them top-to-bottom. I don't think the
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// order really matters that much as long as we define what it is.
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struct A;
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struct B;
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struct C {
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a: A,
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b: B,
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}
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static mut hit: bool = false;
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impl Drop for A {
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fn drop(&mut self) {
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unsafe {
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assert!(!hit);
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hit = true;
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}
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}
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}
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impl Drop for B {
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fn drop(&mut self) {
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unsafe {
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assert!(hit);
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}
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}
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}
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pub fn main() {
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let _c = C { a: A, b: B };
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}
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